Spirochaetes

1. Spirochaetes By Dr. Emad AbdElhameed Morad Lecturer of Medical Microbiology and Immunology

2. Spirochaetes are long, slender, spiral organisms which are motile by periplasmic internal flagellae. • Spirochaetes include three genera: Treponema Borrelia Leptospira

3. Borrelia

4. Relapsing fever Diseases caused by borrelia Lyme disease Vincent angina

5. Relapsing fever • Epidemic relapsing fever: • Caused by Borrelia recurrentis. • Transmitted by lice. • Endemic relapsing fever: • Caused by Borrelia duttoni and Borrelia hermsii. • Transmitted by ticks. * Man is the only host for B. recurrentis and B. duttoni. * Rodents are main the reservoirs of other borrelia.

6. Morphology Gram negativespirochaetes with 5 to 7wide and irregularcoils.

7. Cultural characters Cultured on fluid media containing blood, serum or tissue such as Barbour-Stoenner-Kelly (BSK II) medium. Microaerophilic. Incubated at 30 – 35 degrees. Cultures are monitored for growth by dark field microscope for 4-6 weeks.

8. Clinical picture Mode of infection:lice in epidemic relapsing fever and ticks in endemic type. IP:3 – 10 days. After incubation period:there is sudden onset of fever during which the organism is present in blood. Fever lasts for 4 daysfollowed by afebrile periodof 3 – 10 days. Then the patient develops another bout of fever. 3 – 10 relapses may occur. In fatal cases, borrelia invade heart, liver, spleen and kidney.

9. Why relapse? Antibodies against borrelia appear during fever and destroy the organism and the attack is terminated. Then, borrelia undergo antigenic variation to which the patient has no antibodies and cause relapse.

11. Laboratory diagnosis During the febrile stage: Blood films stained with Giemsa or Leishman stain reveal large number of borrelia.

12. During the afebrile stage: The organism is scanty and blood film is negative. So, we inject the patient blood intraperitoneally in white mice. After 2 – 4 days: Films from tail blood are stained and examined for borrelia. Mice blood is inoculated on BSK II medium.

13. Treatment Penicillin and tetracyclines

14. Lyme disease • This disease is named after the town of lyme, USA where a number of cases were first discovered in 1975. • This disease is caused by Borrelia burgdorferi. • Rodents and deer are the main animal reservoir. • The disease is transmitted to man by ticks.

15. Clinical picture Early stage: Fever Headache Skin lesion called erythema migrans Muscle pain Late stage: Arthritis Myocarditis Meningitis

16. Lyme disease

17. Laboratory diagnosis Specimen:skin biopsy, CSF, joint fluid. PCR is the main diagnostic test. Serological diagnosis: detection of antibodies by ELISA or immunofluorescence. Positive results should be confirmed by Western blot assay.

18. Treatment For early cases, doxycycline or amoxicillin. For late cases, penicillin or ceftriaxone.

19. Vincent angina

20. Pathogenesis • Vincent angina is caused by Borrelia vincenti. • Borrelia vincentiis anaerobic spirochaetewhich lies commensal in healthyhumanmouth. • Under certain conditionswhich cause injury of the mucous membrane, Borrelia vincentitogether with anaerobic cigar shaped fusiform bacilli (fusobacterium) multiply in the lesions causing ulcers. • These ulcers may become covered by pseudomembrane containing pus cells and necrotic tissue. • Vincent angina should be differentiated from diphtheria and follicular tonsillitis.

21. Laboratory diagnosis Specimen:smears prepared from the pseudomembrane. Direct microscopic examination stained with Gram: Gram negative borrelia in large numbers + Gram negative cigar shaped fusiform bacilli + pus cells.

22. GOOD LUCK